The role of the farnesoid X receptor in quadruple anti-tuberculosis drug-induced liver injury.

Anti-tuberculosis drugs-induced liver injury may be associated with the hepatic farnesoid X receptor (FXR). However, the relationship between isoniazid, rifampicin, pyrazinamide and ethambutol (HRZE) coadministration-induced liver injury and FXR has not been clarified. The purpose of this study was to clarify the role of FXR in HRZE-induced liver injury. To measure indices of liver injury, blood samples were collected from clinical tuberculosis patients who had taken HRZE for approximately two months; in these patients serum total bile acids were increased, while other hepatic biochemical indexes showed no significant changes. When Wistar rats were orally administered isoniazid (30 or 60 mg/kg) + rifampicin (45 or 90 mg/kg) + pyrazinamide (150 or 300 mg/kg) + ethambutol (75 or 150 mg/kg) in combination for 15 days, the expression and function of FXR was up-regulated, and hepatic bile acids were decreased. However, following 30 days of HRZE treatment the expression and function of FXR was down-regulated and bile acids accumulated in the liver, suggestive of hepatotoxicity. Treatment of HepaRG cells with HRZE lead to time- and dose- dependent cytotoxicity, with the expression of FXR up-regulated in early stage, but down-regulated with prolonged HRZE treatment, consistent with the results of animal experiments. In summary, HRZE may upregulate FXR with short-term administration, but more prolonged treatment appears to suppress FXR function, resulting in hepatic bile acid accumulation.